Copper-base alloy

ABSTRACT

A copper-base alloy includes 63.5 to 69.0 mass % of Cu, 1.2 to 2.0 mass % of Sn, 0.15 mass % or less of Fe, 0.1 to 2.0 mass % of Pb, 0.01 to 0.2 mass % of Al, 0.06 to 0.15 mass % of Sb, and 0.04 to 0.15 mass % of P when the copper-base alloy includes 63.5 mass % or more and less than 65.0 mass % of Cu, or 0.15 mass % or less of P when the copper-base alloy includes 65.0 to 69.0 mass % of Cu, with the balance being Zn and unavoidable impurities.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of International Patent ApplicationNo. PCT/JP2014/064710, having an international filing date of Jun. 3,2014, which designated the United States, the entirety of which isincorporated herein by reference. Japanese Patent Application No.2013-118383 filed on Jun. 5, 2013 is also incorporated herein byreference in its entirety.

BACKGROUND

The present invention relates to a copper-base alloy. In particular, theinvention relates to a copper-brass alloy that exhibits excellentdezincification resistance, excellent erosion-corrosion resistance,excellent stress corrosion cracking resistance, and the like, and maysuitably be used for parts (e.g., water faucet and valve) that come incontact with water and the like.

A bronze alloy (i.e., copper-base alloy) exhibits excellentdezincification resistance, excellent erosion-corrosion resistance, andexcellent stress corrosion cracking resistance immediately aftercasting. However, since a bronze alloy is more expensive than a brassalloy, a brass alloy that can be used as a substitute for a bronze alloyhas been increasingly desired in recent years.

Japanese Patent No. 3461081 discloses a copper alloy that includes an αphase and a β phase, and exhibits excellent corrosion resistance, thecopper alloy including at least 0.05 to 0.2 wt % of Sn, and 0.05 to 0.3wt % of one element or two or more elements among Sb, As, and P, andhaving a maximum erosion depth (determined by a JBMA test) of 200 μm orless and a solidification temperature of 17° C. or less.

However, the alloy disclosed in Japanese Patent No. 3461081 exhibitsdezincification resistance after being subjected to a heat treatment.

Since the alloy disclosed in Japanese Patent No. 3461081 exhibitsinsufficient erosion-corrosion resistance when used for parts (e.g.,faucet) where fluid flows at a high flow rate, the alloy disclosed inJapanese Patent No. 3461081 can be applied to only a limited number offields.

JP-A-2009-263787 discloses an alloy that includes 61.2 mass % or moreand less than 64.0 mass % of Cu, 0.8 to 2.0 mass % of Sn, 0.04 to 0.15mass % of Sb, 0.4 to 0.7 mass % of Al, 0.5 to 3.0 mass % of Pb, and 1 to200 mass ppm of B, with the balance being Zn and unavoidable impurities,the alloy further including 0.2 to 1.0 mass % of Ni so that the alloyexhibits improved dezincification resistance without requiring a heattreatment, and the ISO maximum dezincification depth of the alloy beingsuppressed to 200 μm or less through macroscopic crystal grainrefinement.

The alloy disclosed in JP-A-2009-263787 meets an ISO maximumdezincification depth of 200 μm or less through refinement achieved by Band Fe. However, when the alloy disclosed in JP-A-2009-263787 issubjected to sand casting that is normally adapted to air-meltingprocess without using a molten metal covering material, B and Fe producean intermetallic compound since the B content is high, and adeterioration in grinding capability may occur.

In particular, it is indispensable to prevent a situation in which B andFe produce an intermetallic compound when the alloy is used for a waterfaucet that is plated after grinding.

An ISO maximum dezincification depth of 200 μm is a standard valueapplied to a dezincification-resistant material. Note that it isnormally desirable that the ISO maximum dezincification depth be 100 μmor less.

The copper-base alloy disclosed in JP-A-2009-263787 substantiallynecessarily includes Ni (see the examples of JP-A-2009-263787).

However, since Ni is an environmentally hazardous substance, and it isexpected that the Ni content in drinking water will be restricted in thenear future, it is undesirable to add Ni to a casting material that isused for a water faucet and a valve.

SUMMARY

An object of the invention is to provide a copper-base alloy (brassalloy) that exhibits excellent dezincification resistance and the likewithout requiring a heat treatment.

Copper-base alloys according to several aspects of the invention exhibitexcellent dezincification resistance without requiring a heat treatmentwhile also exhibiting excellent erosion-corrosion resistance andexcellent stress corrosion cracking resistance, and are classified intoa Pb-containing copper-base alloy and a Bi-containing copper-base alloy.

A Pb-containing copper-base alloy according to one aspect of theinvention includes 63.5 to 69.0% (mass % (hereinafter the same)) of Cu,1.2 to 2.0% of Sn, 0.15% or less of Fe, 0.1 to 2.0% of Pb, 0.01 to 0.2%of Al, 0.06 to 0.15% of Sb, and 0.04 to 0.15% of P when the copper-basealloy includes 63.5% or more and less than 65.0% of Cu, or 0.15% or lessof P when the copper-base alloy includes 65.0 to 69.0% of Cu, with thebalance being Zn and unavoidable impurities.

The copper-base alloy (brass) according to this aspect of the inventionis characterized in that the copper-base alloy exhibits dezincificationresistance that ensures that the ISO maximum dezincification depth is100 μm or less without requiring a heat treatment and the addition of Band Ni that are undesirable for a water faucet.

A material obtained by casting the copper-base alloy does not showcrystal orientation, and suppresses occurrence of cracks (i.e., exhibitsexcellent stress corrosion cracking resistance). A copper-base alloyaccording to another aspect of the invention (that is suitable forcasting) includes 63.5 to 69.0% of Cu, 1.2 to 2.0% of Sn, 0.15% or lessof Fe, 0.1 to 2.0% of Pb, 0.01 to 0.2% of Al, 0.06 to 0.15% of Sb, 0.04to 0.15% of P when the copper-base alloy includes 63.5% or more and lessthan 65.0% of Cu, or 0.15% or less of P when the copper-base alloyincludes 65.0 to 69.0% of Cu, and either or both of at least one elementselected from 0.01 to 0.45% of Te and 0.02 to 0.45% of Se, and at leastone element selected from 0.001 to 0.2% of Mg and 0.005 to 0.2% of Zr,with the balance being Zn and unavoidable impurities.

A Bi-containing copper-base alloy according to another aspect of theinvention includes 63.5 to 69.0% of Cu, 1.2 to 2.0% of Sn, 0.15% or lessof Fe, 0.5 to 1.5% of Bi, 0.01 to 0.2% of Al, 0.06 to 0.15% of Sb, and0.04 to 0.15% of P when the copper-base alloy includes 63.5% or more andless than 65.0% of Cu, or 0.15% or less of P when the copper-base alloyincludes 65.0 to 69.0% of Cu, with the balance being Zn and unavoidableimpurities.

A Bi-containing copper-base alloy according to another aspect of theinvention includes 63.5 to 69.0% of Cu, 1.2 to 2.0% of Sn, 0.15% or lessof Fe, 0.5 to 1.5% of Bi, 0.01 to 0.2% of Al, 0.06 to 0.15% of Sb, 0.04to 0.15% of P when the copper-base alloy includes 63.5% or more and lessthan 65.0% of Cu, or 0.15% or less of P when the copper-base alloyincludes 65.0 to 69.0% of Cu, and either or both of at least one elementselected from 0.01 to 0.45% of Te and 0.02 to 0.45% of Se, and at leastone element selected from 0.001 to 0.2% of Mg and 0.005 to 0.2% of Zr,with the balance being Zn and unavoidable impurities.

The brass alloys according to the aspects of the invention can be usedas a substitute for a bronze alloy.

The brass alloys according to the aspects of the invention meet an ISOmaximum dezincification depth of 100 μm or less without requiring a heattreatment and the addition of B and Ni that are undesirable for an alloyused for applications in which the alloy comes in contact with water.

The brass alloys according to the aspects of the invention also exhibitexcellent erosion-corrosion resistance and excellent stress corrosioncracking resistance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the components and the evaluation results of thecopper-base alloys subjected to evaluation.

FIG. 2 shows the components and the evaluation results of thecopper-base alloys subjected to evaluation.

FIG. 3 is a view illustrating the sampling positions.

FIG. 4 illustrates the erosion-corrosion test method.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The components included in each copper-base alloy according to theembodiments of the invention are described below.

The Cu content is preferably set to 63.5 to 69.0%.

If the Cu content is less than 63.5%, the amount of β phase mayincrease, and a deterioration in corrosion resistance may occur.

It is possible to improve corrosion resistance (e.g., dezincificationresistance) by increasing the Cu content. In this case, however, anincrease in cost and a decrease in strength may occur. Therefore, the Cucontent is preferably set to 63.5 to 69.0%.

Pb improves machinability. The Pb content is set to 0.1% or more when Pbis added. If the Pb content exceeds 2.0%, a decrease in strength mayoccur. Therefore, the Pb content is set to 2.0% or less.

0.5 to 1.5% of Bi may be added instead of Pb in order to improvemachinability.

Sn is necessary for ensuring dezincification resistance anderosion-corrosion resistance. The Sn content must be set to 1.2% or more(preferably 1.5% or more) in order to obtain erosion-corrosionresistance almost equal to that of a bronze material.

If the Sn content exceeds 2.0%, a decrease in elongation (i.e.,mechanical properties) may occur when the copper-base alloy is useddirectly after casting although good dezincification resistance isobtained. The Sn content is preferably set to 1.8% or less in order toensure that high elongation is obtained. Therefore, the Sn content isset to 1.2 to 2.0%, and preferably 1.5 to 1.8%.

Fe easily forms a compound with P, and may impair the effects achievedby P. Therefore, the Fe content is preferably set to 0.15% or less.

Al prevents oxidation of P.

The Al content must be set to 0.01% or more in order to preventoxidation of P.

If the Al content exceeds 0.2%, a deterioration in dezincificationresistance may occur. Therefore, the Al content is set to 0.01 to 0.2%.

The Al content is preferably set to 0.01 to 0.1% from the viewpoint ofdezincification resistance.

Al is also effective for improving fluidity. Note that it suffices toset the Al content to 0.01 to 0.1% in order to obtain fluidity almostequal to that of bronze.

Sb improves dezincification resistance.

The Sb content in the γ phase must be 0.3% or more in order to meet anISO maximum dezincification depth of 100 μm or less without performing aheat treatment.

In this case, the Sb content in the copper-base alloy must be set to0.06% or more.

If the Sb content exceeds 0.15%, the copper-base alloy may becomebrittle. Therefore, the Sb content is set to 0.06 to 0.15%.

The Sb content is preferably set to 0.08 to 0.13% from the viewpoint ofdezincification resistance and mechanical properties.

P improves dezincification resistance together with Sb. Note that P isnecessarily added when the Cu content is less than 65%, and isarbitrarily added when the Cu content is 65% or more.

The P content must be set to 0.04% or more when the Cu content is lessthan 65% in order to meet an ISO maximum dezincification depth of 100 μmor less without performing a heat treatment.

The P content is preferably set to 0.06% or more.

If the P content exceeds 0.15%, segregation may easily occur when thecopper-base alloy is used directly after casting. Therefore, the Pcontent is set to 0.04 to 0.15%.

Note that the copper-base alloy exhibits excellent dezincificationresistance when the Cu content is 65% or more even when the copper-basealloy does not include P. When the Cu content is 65% or more, the Pcontent is set to 0.15% or less (i.e., P is optionally added).

Te improves machinability when the Te content is 0.01% or more. Theupper limit of the Te content is set to 0.45% from the viewpoint ofensuring economic efficiency while improving machinability.

Se improves machinability. Since Se is an expensive material, it isdesirable to minimize the Se content.

The upper limit of the Se content is preferably set to 0.45% or lesssince Se may impair hot workability.

The Se content is preferably set to 0.02 to 0.45%.

Mg improves strength through crystal grain refinement, and improvesfluidity. Mg also has a deoxidation-desulfurization effect.

When molten metal of the copper-base alloy includes 0.001% or more ofMg, S included in the molten metal is removed in the form of MgS.

If the Mg content exceeds 0.2%, the viscosity of the molten metal mayincrease due to oxidation, and casting defects (e.g., inclusion ofoxides) may occur.

Therefore, the Mg content is set to 0.001 to 0.2%.

Zr has a crystal grain refinement effect.

The crystal grain refinement effect is observed when the Zr content is0.005% or more.

Zr has high affinity to oxygen. If the Zr content exceeds 0.2%, theviscosity of the molten metal may increase due to oxidation, and castingdefects (e.g., inclusion of oxides) may occur.

Therefore, the Zr content is set to 0.005 to 0.2% when the Zr is added.

EXAMPLES

Molten metals respectively having the alloy compositions shown in FIGS.1 and 2 were prepared, and cast at about 1000° C. to form a JIS H 5120specimen (obtained using a sand mold) (see FIG. 3), which was cooled(solidified), and then removed from the mold.

Note that a specimen A defined in JIS H 5120 was cast using the moltenmetal.

The balance in FIGS. 1 and 2 includes Zn and unavoidable impurities.

Evaluation Tests (1) Dezincification Resistance Test

A sample was cut from the specimen at each sampling position illustratedin FIG. 3, and immersed in a 12.7 g/l solution of CuCl₂.2H₂O (75±3° C.)for 24 hours, and the dezincification depth was measured (in accordancewith ISO), and evaluated in accordance with the following standard.

A specimen having a dezincification depth of 100 μm or less wasevaluated as acceptable, and a specimen having a dezincification depthof more than 100 μm was evaluated as unacceptable.

Note that the standard dezincification depth was set to be severer thanthe ISO standard (=200 μm).

(2) Tensile Test

A JIS Z 2201 No. 4 specimen that had been sampled from the JIS H 5120specimen A (obtained using a sand mold) and machined, was subjected to atensile test using an Amsler universal testing machine.

A specimen having a strength of more than 200 MPa was evaluated as“Good”, and a specimen having a strength of less than 200 MPa wasevaluated as “Bad”.

A specimen having an elongation of more than 15% was evaluated as “Verygood”, a specimen having an elongation of more than 12% was evaluated as“Good”, and a specimen having an elongation of less than 12% wasevaluated as “Bad”.

(3) Erosion-Corrosion Evaluation Test

A test solution was discharged toward the surface of the specimen usinga testing machine illustrated in FIG. 4, and erosion-corrosion wascaused to occur by utilizing shear force produced by a turbulent flow ofthe test solution flowing through the gap between the specimen and thenozzle to evaluate the maximum corrosion (wear) depth and the state ofcorrosion.

Test solution: CuCl₂.2H₂O (12.7 g/1000 ml)Test temperature: 40° C.Flow rate: 0.2 l/minMaximum flow rate: 0.62 m/secTest time: 7 hours

The evaluation results are shown in FIGS. 1 and 2.

In FIGS. 1 and 2, the item “strength” refers to the tensile strengthmeasured by the tensile test (and evaluated in accordance with the abovestandard), and the item “elongation” refers to the elongation evaluatedin accordance with the above standard.

The item “dezincification depth” refers to the measured value (μm).

The alloys (inventive alloys) of Examples 1 to 20 and 27 to 47 arePb-containing brass alloys, and the alloys (inventive alloys) ofExamples 21 to 24 and 48 to 69 are Bi-containing brass alloys.

The alloys (inventive alloys) of Examples 25 and 26 are Pb-containingbrass alloys that do not include P.

These alloys (in which the content of each component was within thespecific range that falls under the scope of the invention) exhibitedexcellent dezincification resistance without requiring a heat treatment.

In Example 47, the quality targets were satisfied even when the Cucontent was 69.34%. Therefore, it is considered that no problem occurseven when the Cu content exceeds 69.0%.

In Example 39, the quality targets were satisfied even when the Pbcontent was 2.10%. Therefore, no problem occurs even when the Pb contentexceeds 2.0% within a small range.

On the other hand, the alloys of Comparative Examples 101 and 102exhibited poor dezincification resistance since the Cu content was lessthan 63.5%, and the Al content was high.

Moreover, the alloys of Comparative Examples 101 and 102 had anelongation of less than 12%.

The alloy of Comparative Example 113 exhibited poor dezincificationresistance since the P content and the Sb content were 0%.

The alloys of Comparative Examples 103 to 107 exhibited gooddezincification resistance, but had an elongation of less than 12% sincethe Sn content was more than 2.0%.

The alloys of Comparative Examples 108 and 109 exhibited poordezincification resistance since the Cu content was less than 63.5%. Thealloy of Comparative Example 110 exhibited poor dezincificationresistance since the Al content was more than 0.2%.

The alloy of Comparative Example 111 had an elongation of less than 12%since the Sn content was more than 2.0%.

The alloy of Comparative Example 112 exhibited poor dezincificationresistance since the Cu content was less than 65%, and the P content was0%.

The results of the erosion-corrosion evaluation test are discussedbelow.

The alloy (inventive alloy) of Example 3, the alloy of ComparativeExample 113, and a bronze material (CAC406C, Sn: 3.67%, Zn: 5.76%, Pb:4.20%, balance: Cu) were evaluated to compare the results thereof.

The maximum corrosion (wear) depth of the alloy of Example 3 was 66 μm,the maximum corrosion (wear) depth of the alloy of Comparative Example113 was 700 μm, and the maximum corrosion (wear) depth of the bronzematerial was 63 μm.

The alloy of Example 3 was corroded in a layer configuration, while thealloy of Comparative Example 113 was corroded in an annularconfiguration.

Note that the bronze material was corroded in a layer configuration.

It was thus confirmed that the brass alloys according to the embodimentsof the invention can suitably be used as a substitute for a bronzealloy.

The copper-base alloys according to the embodiments of the invention canbe widely used for plumbing products and the like for which highdezincification resistance and high erosion-corrosion resistance arerequired.

The copper-base alloys according to the embodiments of the invention areuseful for reducing the brass alloy production cost since a heattreatment after casting is unnecessary.

Although only some embodiments of the present invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the embodimentswithout materially departing from the novel teachings and advantages ofthis invention. Accordingly, all such modifications are intended to beincluded within the scope of this invention.

What is claimed is:
 1. A copper-base alloy comprising 63.5 to 69.0 mass% of Cu, 1.2 to 2.0 mass % of Sn, 0.15 mass % or less of Fe, 0.1 to 2.0mass % of Pb, 0.01 to 0.2 mass % of Al, 0.06 to 0.15 mass % of Sb, and0.04 to 0.15 mass % of P when the copper-base alloy comprises 63.5 mass% or more and less than 65.0 mass % of Cu, or 0.15 mass % or less of Pwhen the copper-base alloy comprises 65.0 to 69.0 mass % of Cu, with thebalance being Zn and unavoidable impurities.
 2. A copper-base alloycomprising 63.5 to 69.0 mass % of Cu, 1.2 to 2.0 mass % of Sn, 0.15 mass% or less of Fe, 0.1 to 2.0 mass % of Pb, 0.01 to 0.2 mass % of Al, 0.06to 0.15 mass % of Sb, 0.04 to 0.15 mass % of P when the copper-basealloy comprises 63.5 mass % or more and less than 65.0 mass % of Cu, or0.15 mass % or less of P when the copper-base alloy comprises 65.0 to69.0 mass % of Cu, and either or both of at least one element selectedfrom 0.01 to 0.45 mass % of Te and 0.02 to 0.45 mass % of Se, and atleast one element selected from 0.001 to 0.2 mass % of Mg and 0.005 to0.2 mass % of Zr, with the balance being Zn and unavoidable impurities.3. A copper-base alloy comprising 63.5 to 69.0 mass % of Cu, 1.2 to 2.0mass % of Sn, 0.15 mass % or less of Fe, 0.5 to 1.5 mass % of Bi, 0.01to 0.2 mass % of Al, 0.06 to 0.15 mass % of Sb, and 0.04 to 0.15 mass %of P when the copper-base alloy comprises 63.5 mass % or more and lessthan 65.0 mass % of Cu, or 0.15 mass % or less of P when the copper-basealloy comprises 65.0 to 69.0 mass % of Cu, with the balance being Zn andunavoidable impurities.
 4. A copper-base alloy comprising 63.5 to 69.0mass % of Cu, 1.2 to 2.0 mass % of Sn, 0.15 mass % or less of Fe, 0.5 to1.5 mass % of Bi, 0.01 to 0.2 mass % of Al, 0.06 to 0.15 mass % of Sb,0.04 to 0.15 mass % of P when the copper-base alloy comprises 63.5 mass% or more and less than 65.0 mass % of Cu, or 0.15 mass % or less of Pwhen the copper-base alloy comprises 65.0 to 69.0 mass % of Cu, andeither or both of at least one element selected from 0.01 to 0.45 mass %of Te and 0.02 to 0.45 mass % of Se, and at least one element selectedfrom 0.001 to 0.2 mass % of Mg and 0.005 to 0.2 mass % of Zr, with thebalance being Zn and unavoidable impurities.